Experimental study on interface characteristics of PHC short pile foundation under torsional loads

The number of power generation elements in a solar power plant is so huge that a small improvement in construction can result in significant cost savings. Therefore, as a new-type supporting structure for the power generation element, the PHC short pile foundation is being continuously improved. The PHC short pile foundation is formed by pouring concrete into the borehole in which a PHC pipe pile is inserted. The interface between the pile and the concrete is usually smooth. The unbalanced wind loads cause the supporting structures to be subjected to cyclic torsional loads. Therefore, the influences of the pipe pile section on the characteristics of the pile-concrete interface and the torsional response of short pile foundation under static or cyclic torsional loads are considered. Ten groups of full-scale model tests on the PHC short pile foundation with round or flanged pile section under different torsional loads are carried out. The test results show that the shallow interface firstly weakens when the torsional deformation of the PHC short pile foundation meets the stage of nonlinear deformation. Under the cyclic torsional loads, the plastic deformation accumulates and eventually leads to concrete cracking. The flange can increase the joint surface between the precast pile and the concrete, which also can provide occlusion between the interface, so as to restrain the development of the plastic deformation and effectively improve the resistance of short pile foundation to the cyclic torsional loads.